1. Field of the Invention
The present invention generally relates to a substrate processing apparatus for processing substrates with process liquids. Examples of substrates to be processed include semiconductor wafers, glass substrates for liquid crystal displays, glass substrates for plasma displays, substrates for FEDs (field emission displays), substrates for optical discs, substrates for magnet discs, substrates for magnet-optical discs, glass substrates for photomasks, substrates for ceramics, substrates for solar cells, etc.
2. Description of Related Art
In the manufacturing process of semiconductor or liquid crystal display apparatus, substrate processing apparatuses of single substrate processing type for processing substrates one-by-one basis or substrate processing apparatuses of batch type for processing substrates in a lump are used.
The substrate processing apparatus of single substrate processing type described in U.S. Patent Application Publication No. 2004/226655 A1 comprises a spin base for holding a substrate, a plurality of chuck pin disposed on the spin base, an electric motor for rotating the spin base, an atmosphere blocking plate disposed to oppose the spin base, a process liquid nozzle for ejecting process liquid from the center part of the lower face of the atmosphere blocking plate toward the center part of the substrate and a cup encircling the substrate hold by the spin base.
In the above-mentioned conventional substrate processing apparatus, the electric motor rotates the spin base in a condition that the plurality of chuck pin hold the substrate in a horizontal posture. Further, process liquid ejected from the process liquid nozzle is supplied, passing through the center part of the lower face of the atmosphere blocking plate, to the upper face of the substrate in a rotating condition in a condition that the lower face of the atmosphere blocking plate is close to the upper face of the substrate. Receiving centrifugal forces due to rotation of the substrate, process liquid supplied to the upper face of the substrate extends outwardly over the substrate. On reaching a peripheral part of the upper face of the substrate, process liquid is thrown off toward surrounding area of the substrate to be received by the cup.
Process liquid supplied onto the substrate in a rotating condition extends outwardly along over the substrate, moving to peripheral part of the substrate. A plurality of chuck pins are disposed at intervals in a circumferential direction. Most part of process liquid is discharged in a generally horizontal direction from the peripheral part of the substrate, excepting positions on which the chuck pins are placed. In contrast, at the positions where the chuck pins are disposed, process liquid may turn into liquid droplets or mist on reaching the neighborhood of the chuck pins to collide with upper part of the chuck pins. Therefore process liquid supposed to be discharged toward surrounding area of the substrate could reattach onto the substrate in the form of liquid droplets or mist. Also, process liquid reaching at the neighborhood of the chuck pins may flow over the upper part of the chuck pins to be splashed in directions outward and obliquely upward.
Splashes of process liquid splashed over toward surrounding area of the substrate collide with the inner face of the cup to be bounced back to the substrate side. Driven by down flow (downward atmospheric flow), droplets or mist of process liquid generated by collision between the cup and process liquid make move downward while moving inward. Therefore in case when directions of splashes of process liquid from peripheral part of the substrate are generally horizontal, droplets or mist of process liquid move to positions below the substrate. In contrast, in case when directions of splashes of process liquid from peripheral part of the substrate are obliquely upward, droplets or mist of process liquid move in directions inward and obliquely downward toward the upper face of the substrate, thus may resulting in reattachments of process liquid onto the substrate. For this reason, it is required to provide measures to avoid reattachments, such as making the cup larger in a radial direction in order to enlarge the distance between the substrate and the cup in a radial direction.
In the case of a conventional substrate processing apparatus described in U.S. Patent Application Publication No. 2004/226655 A1, because process liquid is supplied onto a substrate in a condition that lower face of the atmosphere blocking plate is close to the upper face of the substrate, possibility of reattachment of process liquid is low even when process liquid splashes in directions outward and obliquely upward from peripheral part of the substrate. However, in the case of this substrate processing apparatus, because the whole area of the upper face of the substrate is covered by the atmosphere blocking plate, it is not possible to move supply target positions of process liquid toward the upper face of the substrate between the central and peripheral part of the substrate. Also, because of the space required to make in order to move the atmosphere blocking plate up and down above the substrate, compared to configurations without such atmosphere blocking plate, height of the substrate processing apparatuses become larger.